Method of assembling tubes and liners in gun manufacture



i iim a a l 3,1416? R. c. MORGAN ET'AL METHOD OF ASSEMBLING TUBES ANDLINERS IN GUN MANUFACTURE Filed Jan. 11, 1922 Patented Nov. l, l fl l.

i s'r REES C. MORGAN AND JOHN F. PELLY, 0F BETHLEHEM, PENNSYLVANIA,ASSIGNORS TO BETHLEHEM. STEEL COMPANY, OF BETHLEHEM, PENNSYLVANIA, ACORPORA- TION OF PENNSYLVANIA.

METHOD OF ASSEMBLING- TUBES AND LINERS IN GUN IEANUFACTURE.

Application filed January 11,1922. Serial No. 528,573.

To all whom it may concern:

Be it known that we, Runs C. MORGAN and J orrn F. PELLY, citizens of theUnited States, and residing at Bethlehem, Lehigh County, State ofPennsylvania, respectively, have invented certain new and usefulImprovements in Methods of Assembling Tubes and Liners in GunManufacture, o which the following is a specification.

This invention relates to methods of assembling liners and tubes of gunsof large caliber.

It is a practically universal practice in gun manufacture to provide theliner with one or more forwardly facing annular shoulders which aredesigned to abut against corresponding rearwardly facing annularshoulders formed on the inside of the tube. These shoulders are intendedto prevent the liner from creeping toward the muzzle of the gun inservice, due to the mandrelling-out ef fect of the projectiles passingthrough the bore at high speeds, and to the eifect of the powderpressure. In the shrinkage method of assembling the tube and liner thelatter is usually placed in a vertical position and either cooledinternally by water jets or kept at ordinary room or shop temperature,while the tube is heated and expanded so that the diameter of its boreis greater than the outer diameter of the liner, after which the tube islowered over the liner and cooled, when it frictionally grips the linerwith great force, in a well known manner. It is essential that the oneor more shoulders of the liner be seated against the correspondingshoulders of the tube when the assembly is complete, otherwise the linerwill creep forward in service, which is objectionable for a number ofreasons.

Heretofore it has been very diificult to assemble the tube and liner insuch manner that the corresponding shoulder or shoulders are properlyseated, largely due to the fact that the hot tube on being droppedaround the cool liner causes the latter to expand and contact with thetube at a number of points along its length, and very often toward themuzzle end of the gun, before contact is made at the breech end. Also,as the muzzle end of a tube is of less thickness it cools more quicklyand tends to grip the liner first. As the tube contracts longitudinally,as well as-diametrically upon coolin is obvious that if it has firstgripped the liner in front of a shoulder, that as it contractslongitudlnally the shoulder of the tube will recede from the shoulder ofthe liner, to cause an undesirable gap between the shoulders. If thetube were to first grip the liner in rear of the forwardly facingshoulder of the latter, obviously the shoulders would be drawn togetheras the tube cools, but this practically never takes place because of therelatively great thickness of the tube at the breech end where it maycomprise several concentric cylinders, as compared with its thickness atthe muzzle, the heavier breech end being much slower in cooling.

Furthermore, as a direct result of the frictional gripping of tube andliner at-a number of points as the tube cools, the liner is forceablylongitudinally contracted by the heavier cooling and longitudinallycontracting tube and the resulting gun has a liner which is not onlyunder an initial longitudinal compressive stress, which is veryundesirable, but in which the fconr pression, or the actual shorteningof the diameter of the bore of the liner may Vary widely from thetheoretical compression desired.

It is the object of thepresent invention to provide a method ofassembling tubes and liners by shrinkage whereby the correspondingshoulders of tube and liner are firmly and positively seated andlongitudinal shortening of the liner prevented so that the liner of theresulting gun is not under initial longitudinal compression; and inwhich the actual compression realized closely approXi mates the desiredtheoretical compression.

The method will be described below, and an apparatus for carrying it outis illustrated in the accompanying drawings in which;

Figure 1 is a longitudinal sectional View through an assembled tube andliner, showing the apparatus in operative position; and Figure '2 is anenlarged partial section through a portion of the apparatus. i

In application, Serial No. 528,575, filed January 11, 1922, is describedand claimed an apparatus for holding a liner againstlongitudinalcontraction as itis assembled with a tube, and in Figure 1 of thedrawings of the present application we have illusessentially a steelshaft 10 which extends.

through the bore of the linenbeing held centrally therein by annularspacing members .11. Th'e'upper end of this bar 10 has connectedtheretoa'plug 12, which has screwthreaded engagement with the muzzle end of theliner itself,and the-breech end of the bar 10 is connected or secured toa power device preferably hydraulic, indicated at 13. Swinging arms '14having hooked ends 15 arealsovsecured to the power mechanism 13, whichis adapted when actuated, to effect relative movement between the bar 10and the arms 14:, drawing the tube rearwardly and moving the linerforwardly. Because of the engaging annular shoulders of the tube andliner, indicated at 16, the liner is held against longitudinalcontraction between the offset 16 and itsmuzzle end, thereby insuring,when the assembly has been completed, a gun in which the liner is "underno initial longitudinal compression.

In order to insure that "the tube and liner shall first engage at thebreech or first r shoulder of each, means is provided "for 'he'atingtheliner at this section sulfrciently 'to cause an expansion thereof tosuch an extent "thatitwilliwithout fafil be the first section "to engagethe corresponding section of the tube as the latter graduallycontractswhile cooling. "It is not necessary to heat the liner to "a hightemperature 'to bring about "thisre'sult, and we thereforepreferablyemploy hot water or steam as a heatingmedium. "On the shaft 10are positioned rings .19 and'QO, clearly illustrated [in section inFigure 2, these rings being provided with packing strips. The uppermostpacking stripsfare designed to permit a slight leakage offluid aroundthem and the .plug '12 is providedwitha vent '12 to 'allowthe escape ofair. Conduits are formed .in the rear portion ofthe column 10 for thepassage of fluid, a steam or hot water inlet conduit being indicatedat'21 and an outlet conduit at 22. To the outer ends ofthese conduitsmay be connected flexible fluid conduits for conducting the heatedfluid. to the conduit 21,.and away from the outlet of the conduit 22. Bythese means steam or hot water may beeontinually circulated :in theannular space around shaft 10; and between :the rings 19mm 20, therebyheating this section of the liner and causing itsexpansion in thedesired manner.

In carrying out the method the plug 12 is first screwed "into preparedthreads in the muzzle end of the liner and the liner placed .aroundvertical shaft 10,being-supported only at its anuzzleend. The heatedtube is then lowered into position over the liner, with its entireweight resting on the shoulders of the liner. Steam is then introducedinto the annular space between rings 19 and 20 and the flow of steam iskept up until the liner has been heated sufliciently to give asufficientdiametrical expansion to insure that the expanded section will be thefirst section to contact with thecooling and contracting tube. Leakageof steam around the upper rings 20 causes the heating and expanding of asection of the liner above this ring and, due to the rising steam, thise2;- pansion slowly progresses upwardly. 'VVhen the steam has been shutoff the hydraulic power mechanism is operated to exert an upi ward forceat the muzzle of the liner and a downward force on the tube topositively prevent the longitudinal contraction .of the tube or toslightly stretch the same, if found desirable. Preferably the power isapplied in stages, being increased from time to time during the coolingof the tube.

The heat from the internal heating plant and the heat passing to theliner by conduction after it 'has engaged the hot tube is graduallytransmitted in both directions along the liner, causing-the successiveexpansionof sections and gradual gripping of liner and tube throughouttheir lengths. flhegradualheating of the liner also causes its'gradualextension in both directions. As a iresult'of this method or assemblingthe shoulders of the tube and .liner are not only correctly seated butlongitudinal compres- SIVB stresses in the liner of the finished gun arepractically avoided.

"Th apparatus may be modified in various ways as "will be obvious tothose skilled in the art. It is simple, inexpensive to construct and,operate and thoroughly 'effi- 'cient, being effective in causing theliner and tube togripgprimarily at any section selected and'therebyenabling the operator in the shrink pit to be assured that in theassembling operation the various shoulders of the tube and 'liner areproperly seated and that objectionable longitudinal compressive stresseswill not bepresent.

Having thus described the invention "what we claim as new and desire tosecure 'by Letters Patent is:

1. 'The method of assembling a tube and linerby shrinking,consisting inexpanding the tube by heat, placing the tube over the liner, .andexpanding a section of the liner by heat.

2. The method of assembling a tube which diminishes in thickness fromone end to the other and a liner by shrinking, consisting in expandingthe tube by heat, in

3. A method of assembling the tube and liner of a built-up gun havingcooperating shoulders near the breech end, consisting in expanding thetube by heat, in placing the tube around the liner, and in expanding asection of the liner at, or in the region of, the shoulders While thetube is cooling.

a. A method of assembling a tube and liner, said tube being thicker atone end than at the other, consisting in expanding the tube by heat, inplacing the tube around the liner, and in expanding a section of theliner in the vicinity of the thick end of the tube while the latter iscooling.

5. A method of assembling a tube and liner, said tube being thicker atone end than at the other, consisting in expanding the tube by heat, inplacing the tube around the liner, and in expanding a section of theliner in the vicinity of the thick end of the tube by applying heatinternally of the liner while at the same time allowing the tube tocool.

, 6. A method of assembling a tube and liner having shoulders to beseated consisting in expanding by heat thetube along its entire length,placing the expanded tube over the liner, expanding a limited section ofthe liner by applying steam to the interior of said section of theliner, and cooling the tube to cause it to shrink and grip the liner,throughout the length thereof, but first at the previously expandedsection of the liner.

7. A method of assembling a tube and a liner having shoulders to beseated, consisting in expanding the tube by heat throughout its length,in placing the expanded tube over the liner with the shoulders incontact, in expanding the liner diametrically at the region of ashoulder thereof near one end to secure contact of the tube and linerfirst at that region while at the same time allowing the tube to cool.

8. A method of assembling the tube and the liner of a built-up gun, thetube having a plurality of interior shoulders facing the breech end andthe liner having a plurality of shoulders facing the muzzle end, inexpanding the tube by heat throughout its length, in placing the tubeover the liner with at least the shoulder near the breech end in contactwith the corresponding liner shoulder, and in expanding a section of theliner in the vicinity of the shoulders nearest the breech end to securecontact of the liner with the tube first in that region and then inprogressively expanding the liner by heat to secure progressive contactthereof with the tube from said region toward the muzzle end while atthe sametinie allowing the tube to cool.

9. The method of assembling a tube and liner, consisting in expandingthe tube by heat, placing the tube over the liner, expanding a sectionof the liner by heat, stretching or elongating said liner and shrinkingthe tube on the liner while the latter is in an extended condition.

10. The method of assembling built-up guns, consisting in heating andexpanding a tube, placing the tube over a liner, expanding a section ofthe liner by heat, shrinking said tube upon the liner, and

positively preventing longitudinal contraction of said liner.

In testimony whereof we hereunto affix our signatures.

REES o. MORGAN. 5 JOHN F. PELLY.

